but then to answer my question I guess it all depends on what my tds will be after the ro to say how long the di would last
I use one of those small 10" refillable housings just before hose reel on the van, Buy my water in from a mate but not always 000 tds hence why. Usually around 006 , cartridge lasts for a good 2000 liters or so before it starts to creep up. Not that its a biggy , anything under 010 ppm am happy to work all day with anyhow.
like you say, depends really on your input tds, what i will say though is I like how easy it is to empty and refill.
